Method for determining a dopant concentration in a semiconductor sample

Abstract

A method is described for determining a dopant concentration on a surface and/or in layer region lying close to the surface of a semiconductor sample using an atomic force microscope, whose leaf-spring tip is brought into contact with the semiconductor sample, forming a Schottky barrier, wherein an electric alternating potential is applied between the spring-leaf tip and the semiconductor sample in the region of the Schottky barrier in such a way that a space charge region inside the semiconductor sample defining the three-dimensional extension of the Schottky barrier is excited and begins to oscillate within the confines of its spatial extension, said oscillations are transmitted to the leaf-spring, are detected and form the basis for determining the dopant concentration.

1. A method for determining a dopant concentration on a surface and/or in a layer region spaced from the surface of a semiconductor sample using an atomic force microscope including a leaf-spring tip which is brought into contact with the semiconductor sample comprising:
 forming a Schottky barrier; 
 applying an electrical alternating potential between the spring-leaf tip and the semiconductor sample in a region of the Schottky barrier to excite a space charge region inside the semiconductor sample defining a three-dimensional extension of the Schottky barrier, which oscillates dimensionally within a spatial extension thereof; 
 transmitting the dimensional oscillations to the leaf-spring; 
 detecting the dimensional oscillations with the leaf-spring; and 
 in response to detecting the dimensional oscillations, determining the dopant concentration. 
 
     
     
       2. The method according to  claim 1 , wherein:
 the oscillations are excited to produce a contact resonance between the leaf spring and the semiconductor sample. 
 
     
     
       3. The method according to  claim 1 , comprising:
 transmitting a contact resonance frequency, an amplitude and/or a phase of the oscillations to the leaf spring for determining the dopant concentration. 
 
     
     
       4. The method according to  claim 2 , wherein:
 a contact resonance frequency, an amplitude and/or a phase of the oscillations to the leaf spring for determining the dopant concentration. 
 
     
     
       5. The method according to  claim 3 , wherein:
 determination of the dopant concentration utilizes a signal feedback for detecting a variation the contact resonance frequency. 
 
     
     
       6. The method according to  claim 4 , wherein:
 determination of the dopant concentration utilizes a signal feedback for detecting a variation of the contact resonance frequency. 
 
     
     
       7. The method according to  claim 5 , wherein:
 the dopant concentration is determined by detecting a variation in amplitude and/or phase of the oscillations of the leaf spring as a function of a location. 
 
     
     
       8. The method according to  claim 6 , wherein:
 the dopant concentration is determined by detecting a variation in amplitude and/or phase of the oscillations of the leaf spring as a function of a location. 
 
     
     
       9. The method according to  claim 1 ,
 applying a DC potential to the leaf spring. 
 
     
     
       10. The method according to  claim 2 ,
 applying a DC potential to the leaf spring. 
 
     
     
       11. The method according to  claim 3 ,
 applying a DC potential to the leaf spring. 
 
     
     
       12. The method according to  claim 4 ,
 applying a DC potential to the leaf spring. 
 
     
     
       13. The method according to  claim 5 ,
 applying a DC potential to the leaf spring. 
 
     
     
       14. The method according to  claim 6 ,
 applying a DC potential to the leaf spring. 
 
     
     
       15. The method according to  claim 7 ,
 applying a DC potential to the leaf spring. 
 
     
     
       16. The method according to  claim 8 ,
 applying a DC potential to the leaf spring.